Footwear with balancing structure

ABSTRACT

The inventive subject matter is directed to a sole unit for an item of footwear having a forefoot region, a midfoot region and a rearfoot region. The mid foot region includes a balancing structure having a curved surface profile that rotates around (i) an axis for fore-aft pivoting or balancing and/or (ii) an axis for lateral-medial pivoting or balancing, when the item of footwear is under a normal load of a user.

RELATED APPLICATIONS

This application claims priority to and the benefit of U.S. Provisional Patent Application No. 61/177,215, filed May 11, 2009, by Simon Luthi et al., entitled FOOTWEAR WITH BALANCING STRUCTURE, which is incorporated herein by reference as if included in its entirety for all purposes.

BACKGROUND

The inventive subject matter disclosed herein generally relates to various novel embodiments of a sole system for footwear. More particularly, the inventive subject matter is directed to a sole configuration that in use provides a midfoot region that serves as a fore-aft balance point and/or lateral/medial balancing or pivoting point.

Over recent years there has been increasing awareness of the vital role that musculature health benefits from a healthy and strong, flexible set of core muscles. Stable core provides the foundation for all day to day activity, stabilizing and balancing the lower back and pelvic region, neck, upper back and shoulder blade region. Additionally it strengthens the muscles of the pelvic floor region.

Common complaints that may be attributed to inactive or weak core muscles include: low back pain, shoulder and neck pain, hamstring tightness. Core muscles may also suffer during and after pregnancy, causing leg pain, groin pain, and knee pain.

Research has shown that when a person has back pain/leg pain and neck/shoulder blade pain the muscles around these areas ‘switch off’ during daily or routine activities, which breaks down the stabilizing ability of the muscle system. When the pain resolves the muscles do not automatically ‘switch on’ again, leading to ongoing poor function and potential for recurrence of pain.

The core muscles can be all or any of this set: rectus abdominus, transverse abdominus, internal and external obliques, pelvic floor, multifidi, erector spinae, longissimus throacis, diaphragm, and gluteus maximus and medius. Weakness and inflexibility in core muscles has been attributed to or contributed to the conditions such as back pain, sciatica, for example. Development of core muscles has also been a part of rehabilitation and conditioning programs for recovery from or prevention of injuries and degenerative conditions.

Athletic and dance performance can also be improved with improvements in an individual's ability to balance. Unfortunately, balancing exercises and drills typically require trips to the gym or other workout location; they are not easily conducted in connection with every-day activities.

One or more of the core muscles are activated when a person is engaged in certain upright balancing positions or movements. Unfortunately, few people find the time to make an effort on a day-to-day basis to engage in balancing or other fitness activities that help activate and thereby strengthen and maintain core muscles. Accordingly, there is a need for apparatuses and methods that will allow people to make core strength development and maintenance an anytime, everyday part of their lives.

There is also a need for systems that will help athletes, dancers and others improve their balance with convenient, anytime, anyplace apparatuses and methods.

SUMMARY

The inventive subject matter overcomes the aforementioned problems and others via an innovative design for a sole unit for footwear. It is believed that the inventive subject matter helps strengthen muscles, retrain and activate inactive muscles, correct movement patterns, and help prevent recurrence and long term disability.

The inventive subject matter is directed to a sole unit for an item of footwear having a forefoot region, a midfoot region and a rearfoot region. The mid foot region includes a balancing structure having a curved surface profile that rotates around (i) an axis for fore-aft pivoting or balancing and/or (ii) an axis for lateral-medial pivoting or balancing, when the item of footwear is under a normal load of a user.

These and other embodiments are described in more detail in the following detailed descriptions and the figures.

The foregoing is not intended to be an exhaustive list of embodiments and features of the present inventive concept. Persons skilled in the art are capable of appreciating other embodiments and features from the following detailed description in conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The following figures show embodiments according to the inventive subject matter, unless noted as showing prior art.

FIG. 1 shows a side elevation of one possible embodiment of an item of footwear (left shoe) with a midfoot structure for balancing.

FIG. 2A shows a bottom perspective view of the sole unit from the embodiment of FIG. 1.

FIG. 2B shows an assembly view of possible components for the sole unit of FIGS. 1-2A.

FIG. 3A shows a side elevational view of certain assembled components from the sole unit of FIG. 2B.

FIG. 3B shows a bottom elevational view of the sole unit of FIG. 3A.

FIG. 4 shows a side elevational view of another possible embodiment of an item of footwear (left shoe), a sandal-style shoe, with a midfoot structure for balancing.

FIG. 5 shows a side elevational view of another possible embodiment of an item of footwear (left shoe), a high-heel platform-style shoe, with a midfoot structure for balancing.

DETAILED DESCRIPTION

Representative embodiments according to the inventive subject matter are shown in FIGS. 1-5, wherein the same or generally similar features share common reference numerals.

The inventive subject matter is directed to a sole unit for an item of footwear having a forefoot region, a midfoot region and a rearfoot region. The mid foot region includes a balancing structure having a curved surface profile that rotates around (i) an axis for fore-aft pivoting or balancing and/or (ii) an axis for lateral-medial pivoting or balancing, when the item of footwear is under a normal load of a user.

Before expanding upon the foregoing and other inventive features, an overview of foot anatomy will help illustrate the invention, and facilitate a better understanding of it. The forefoot is composed of five toes and their connecting long bones, the metatarsals. Each toe, or phalanx, is made up of small bones, the phalanges. The big toe, or hallux has two phalanges, two joints, the interphalangeal joints; and two tiny, round sesamoid bones that enable it to move up and down. The other four toes each have three bones and two joints. The second row of phalanges is connected to the metatarsal heads by five metatarsal phalangeal joints at the ball of the foot, i.e., where the foot is normally at its widest.

The midfoot has five irregularly shaped tarsal bones, which form the foot's arch. The rearfoot is composed of three joints and links the midfoot to the ankle (talus). The top of the talus is connected to the two long bones of the lower leg (tibia and fibula), forming a hinge that allows the foot to move up and down (dorsiflexion/plantar flexion).

The heel bone (calcaneus) is the largest bone in the foot. It joins the talus to form the subtalar joint, which enables the foot to rotate at the ankle (eversion/inversion).

The inventive subject matter is implemented through a sole unit that provides a balancing structure that enables balancing along one or more axes of the shoe as described below. When the upper of the shoe balances on the balance structure, core muscles are activated and benefited as described in the background and summary sections.

A sole unit may be broken down into regions generally corresponding to the forefoot, midfoot, and heel bone (which is also referred to herein as the “rearfoot”).

As used herein, “footwear” refers to any item for supporting the foot and engaging the ground and encompasses shoes, sandals, boots, slippers, over-shoes, athletic shoes, dance shoes, and other footwear articles. “Cushioning elements” refers to basic shock absorbing, energy return, and/or protective underfoot materials or structures that are intended to react to the forces of foot strike by providing force attenuation, dissipation, dampening, or energy return (spring), which are typically included on sports and athletic shoes. Traditionally, a cushioning element comprises a consistent and uniform layer of shock absorbing and protective material, such as such as EVA or polyurethane, placed in a shoe between the foot and the ground. However, in relatively recent years there has been a trend towards customized placements of varying cushioning materials and structures under a foot. Nowadays, common cushioning elements may be based on EVA or polyurethane foam, visco-elastomers of foam or gels, fluid filled bladders, mechanical springs or resiliently collapsible mechanical structures, fluid (e.g., air, viscous gel) springs, or any combination of the foregoing.

For example polymer spring units have been placed in portions in the sole unit receiver, particularly the heel portion, and in some cases the forefoot portion. Mechanical polymer springs may be formed from an injected thermoplastic, such as Hytrel polymer, PEBAX, and TPU, as well as other resilient polymers, thermo-set plastics, and metallic materials known in the art, alone or in combination. See, for example, U.S. Pat. No. 5,461,800, which is hereby incorporated by reference in its entirety. The U.S. Pat. No. 5,461,800 discloses a foamless midsole unit, comprising upper and lower plates sandwiching transverse cylindrical units formed of resilient polymer. See also, for example, U.S. Pat. Nos. 4,910,884, 6,625,905, and 5,337,492. Other forms of mechanical springs, such as leaf-spring structures are also contemplated.

As used herein a “sole unit” generally may comprise a midsole or cushioning element for energy absorption and/or return; or an outsole material for surface contact and abrasion resistance and/or traction; or a single unit providing such midsole or outsole functions. While a sole unit would generally extend the length of the shoe, a sole unit could also comprise a unit that extends for a lesser area, such as, just the forefoot or rearfoot portion, or some other area of lesser length or width.

A sole unit may include cushioning elements in accordance with any of the foregoing cushioning elements. Contemplated fabrication methods for the sole unit components include molding, injection molding, blow molding, direct-injection molding, one-time molding, composite molding, insert molding, co-molding separate materials, or other techniques known in the art, alone or in combination. Contemplated fabrication or assembly methods include adhesives, bonding agents, welding, mechanical bonding, or interlocking shapes, alone or in combination.

Dampening elements, which are a form of cushioning element (as defined herein), may also be incorporated into the sole units and/or sole unit receivers disclosed herein. “Dampening” generally refers to the ability of certain materials to reduce the amplitude of oscillations, vibrations, or waves. In footwear, shock from impact may generate compression waves or other vibrations within the sole system. Contemplated dampening materials include visco-elastomers. In some instances, plain elastomer materials may be used as dampeners; however, they may not provide as desirable dampening qualities on the spring unit as a visco-elastomer. Example materials for a visco-elastic dampener include any number of polymers, including polyurethanes and polyethylenes in foam or gel form, fabricated by conventional molding practices or by film. Other suitable visco-elastomers are known to persons skilled in the art. Contemplated fabrication methods for visco-elastomers include molding, injection molding, blow molding, direct-injection molding, one-time molding, composite molding, insert molding, co-molding separate materials, or other techniques known in the art, alone or in combination. Contemplated fabrication or assembly methods include adhesives, bonding agents, welding, mechanical bonding, or other mechanical or chemical fastening means know to persons in the art, alone or in combination.

The outsole for a sole assembly may include rubber, leather, felts, EVA, foam, and other cushioning technologies, and combinations of the foregoing. The outsole may have any kind of traction surface, including, for example, smooth and patterned surfaces, cleated surfaces, and spiked surfaces. As is well-known in the art, a single unit may be formed to provide both a cushioning element and outsole functionalities. For example, EVA and PU materials may be formed into a multifunctional unit.

FIGS. 1-3B show one possible embodiment of an item of footwear 10 with an upper 12 and a sole unit 14. The sole unit has a midfoot region having a midfoot structure 16 for balancing. The midfoot balancing structure may be disposed in and protrudes from a recessed midfoot region, as seen best in FIG. 2A. The recessed area from which balancing structure 16 protrudes is defined by parallel arms 18 a and 18 b that have a concave shape and run along lateral and medial sides of the sole unit.

The balancing structure provides a surface profile 20 that is raised relative to the forefoot regions and rearfoot regions and which thereby allows a user to balance between or pivot on an off the forefoot and rearfoot regions. The balancing structure may also provide a surface profile 20 that is raised relative to lateral and/or medial sides of the sole to provide for balancing between or pivoting on and off the lateral and/or medial sides of the shoe. The surface profile provides at least one tangential point 22 for pivotal rotation of the sole unit. A single tangential point would be provided in the case of a surface profile in the nature of a hemisphere. However, more than one tangential point may be provided for surface contact along an axis of rotation, as noted below in the example of a balancing structure in the nature of a cylinder. The pivoting occurs around a rotational center point 24, which may be at an intersection of orthogonal axes X-X, Y-Y, and Z-Z, as indicated in FIGS. 3A-3B. Axis X-X runs vertically in between the lateral and medial sides of the sole unit. Axis Y-Y runs horizontally along the longitudinal axis of the sole unit. And axis Z-Z runs transversely to the longitudinal axis of the sole unit, through the midfoot's lateral and medial sides. In the case of fore-aft balancing or pivoting, the balancing structure rotates around axis Z-Z. In the case of lateral-medial balancing or pivoting, the balancing structure rotates around axis Y-Y, as indicated by the arrows. Heel-to-toe rotation may occur around axis X-X.

The balancing structure may be resilient in nature, e.g., made of a foamed EVA or PU or a mechanical or elastomeric spring structure. Alternatively, it may be made of a non-resilient material or structure using, e.g., metal, wood, hard plastic, etc.

The balancing structure 16 may be raised by making the physical dimensions of the balancing structure thicker than adjacent forefoot or midfoot materials or structures so that the balancing surface protrudes. Alternatively, the balancing structure need not protrude relative to the forefoot or rearfoot but can be coplanar or even relatively recessed when the item of footwear is not under the normal load of a wearer. By selecting materials or structures for the forefoot and rearfoot that will selectively compress or collapse under the normal loads (e.g., standing, walking, running, dancing, etc) of a wearer relative to the balancing structure, there is an effective protrusion of the balancing structure to allow for balancing or pivoting.

As the Figures indicate, balancing structure 16 is located substantially or entirely within the midfoot. However, so long as the balancing surface profile 16, with a center point of rotation for one or both of axes Z-Z and Y-Y, is generally disposed in the midfoot region, the balancing structure may extend into the midfoot or rearfoot regions. An example of a balancing structure that might have just one of the axes Z-Z and Y-Y in the midfoot region, is a cylinder with ends disposed along axis Z-Z. The cylinder would rotate around that axis but not around axis Y-Y. A cylinder also provides a continuum of tangential points 22. An axis for rotation around axis Y-Y could be provided in the forefoot or rearfoot region, e.g., a cylinder with ends oriented along axis Y-Y or a hemispherical like structure which could provide for rotation along both axes X-X and Y-Y.

In the embodiment shown, balancing structure 16 is rounded so as to allow fore-aft rocking and lateral-medial rocking. It also allows toe-heel swiveling. In this embodiment, the balancing structure is more oblong or egg-shaped, with the elongated dimension following the Y-Y axis along the longitudinal axis of the sole unit. This configuration helps provide for stability and control. The curvatures may be relatively shallow along the Y-Y and/or Z-Z axes to allow for more gradual fore-aft rocking than would be provided by a more hemispherical shape, for example, with steeper curves. However, from the teachings herein, persons skilled in the art will recognize the structural configuration can be in various forms to achieve desired degrees of rocking, stability and controllability. For example, for more aggressive balancing and control, a larger, more-hemispherical configuration may be implemented.

As seen in the various figures, the sole unit may provide toe-spring so that the forefoot region in an unloaded condition curves upwardly a predetermined degree. Such curvature may facilitate fore-aft pivoting.

The balancing structure 16 need not be rounded to allow pivoting; it can also be in other geometrical forms that allow for pivoting around an axis, for example, polygonal shapes of more than four sides that approximate a curve. Any actually curved surface profiles or approximately curved surface profiles that serve to provide rotation around an axis shall be deemed to have a “curved surface profile,” as used herein. It could even be square by constructing the outer portion to have a lower durometer than an inner portion so that under load the outer portion compresses or collapses to a shape that allows pivoting. Any such functionally curved surface profiles shall also be a “curved surface profile, as used herein”.

The sole unit may be formed as a single monolithic unit out of known or to be discovered molded materials. A monolithic structure may have a homogeneous or heterogeneous composition. It may have varying material properties, such as varying density, durometer, spring rates, etc. The sole unit may also be an assembly of components. An example of a sole unit have multiple components is shown in FIGS. 2A-3B. Upper 12 is attached to a core layer 26 that includes balancing structure 16. The balancing structure could also be disposed on other components of the sole unit. Or it could be a discrete unit affixed to, pocketed within, sandwiched between, or otherwise structurally coupled to the sole unit. A full length core layer that is relatively stiff but with some resilience can advantageously provide lever arms on either side of the balancing structure to help with balancing and pivoting. It can also help distribute forces.

At least the balancing structure of the core layer would be of a relatively high density EVA or other resilient material (all durometer expressed herein are Asker C) so as to provide the pivoting functions discussed above relative to adjacent regions or sections of the sole unit.

Disposed below core layer 26 is a relatively low durometer stability layer. The stability layer 28 may be, for example, an EVA having a density and durometer that is relatively lower than the core layer 26. The stability layer in this example provides a window framed in part by arms 18A and 18B. The window allows the balance structure 16 on the core layer to extend through and be exposed to the ground in use. The stability layer provides structural stability and/or serves as a cushioning element, as does a traditional midsole for an athletic shoe.

In some embodiments, the balancing structure in the midfoot region has a relatively higher overall durometer than the overall durometer in the forefoot region or rearfoot region. In such embodiments, there should be a difference of at least about 10 C. In some embodiment, the core layer or at least the balancing structure in the midfoot region has a durometer of from about 60 C to about 80 C and the stability layer in a forefoot or rearfoot region adjacent the stability structure has a durometer of from about 40 to about 50 C.

Disposed below the forefoot region of the stability layer is forefoot outsole layer 32. Disposed below the rearfoot region of the stability layer is forefoot outsole layer 34. These layers may be, for example, rubber or other known or to be discovered material.

Although the core layer 26 and stability layer 28 are shown as a full-length structures, either could reside under just a portion of the foot, with other structures extending to other areas. Conversely, although outsole layers 32 and 34 are shown each covering just a portion of the foot, a full length outsole could be provided. A full length outsole could have a window similar to window 30 or instead have a thin layer of material in the area for the window that conforms to the shape of the balancing structure. Alternatively, the balancing structure could be formed in and of outsole material.

The sole system shown can have the components permanently affixed together or removably fixed together for interchange or replacement of components. The latter form of assembly shall be referred to as a modular construction. One advantage of a modular assembly is that a user can not only replace worn components, but the user can also tune the assembly for a desired effect. For example, a set of balancing structures could be provided ranging from ones with relatively shallower curves or less protrusion to ones with deeper curves and greater protrusion. The balancing structure with shallower curves would be used initially for easier balancing and control. The user would progress to curves or protrusion profiles that would more aggressively challenge and develop the users balance, control and muscle development.

The inventive subject matter can be used in a variety of shoe types. For example, FIG. 4 shows a side elevational view of another possible embodiment of an item of footwear, a sandal-style shoe, with a midfoot structure for balancing. FIG. 5 shows a side elevational view of another possible embodiment of an item of footwear, a high-heel platform-style shoe, with a midfoot structure for balancing.

Persons skilled in the art will recognize that many modifications and variations are possible in the details, materials, and arrangements of the parts and actions which have been described and illustrated in order to explain the nature of the inventive subject matter, and that such modifications and variations do not depart from the spirit and scope of the teachings and claims contained therein.

All patent and non-patent literature cited herein is hereby incorporated by references in its entirety for all purposes. 

1. A sole unit for an item of footwear, comprising: a forefoot region, a midfoot region and a rearfoot region; wherein the mid foot region comprises a balancing structure having a curved surface profile that rotates around (i) an axis for fore-aft pivoting or balancing and/or (ii) an axis for lateral-medial pivoting or balancing, when the item of footwear is under a normal load of a user.
 2. The sole unit of claim 1 wherein the a balance structure is defined by material having a higher durometer than the durometer of the adjacent forefoot and rearfoot regions so that the forefoot and rearfoot regions preferentially compress relative to the midfoot region, leaving the midfoot region as a protrusion for balancing.
 3. The sole unit of claim 1 wherein the midfoot region has a durometer of about 60 C to about 80 C, and the forefoot and midfoot regions each have a durometer at least 10 C below the durometer of the midfoot region.
 4. The sole unit of claim 3 wherein the durometer of the balancing structure is about 60 C to about 80 C.
 5. The sole unit of claim 1 wherein the balancing structure comprises a rounded structure protruding from a recessed midfoot area.
 6. The sole unit of claim 5 wherein the rounding of the structure allows for fore-aft rocking.
 7. The sole unit of claim 5 wherein the rounding of the structure allows for lateral-medial rocking.
 8. The sole unit of claim 5 where the rounding of the structure allows for both fore-aft rocking and lateral-medial rocking.
 9. The sole unit of claim 1 wherein the curved profile is provided by a polygonal structure having more than four sides.
 10. The sole unit of claim 1 wherein the curved profile is provided by a balancing structure having varying durometer.
 11. The sole unit of claim 1 wherein the sole unit comprises a monolithic structure.
 12. The sole unit of claim 1 wherein the monolithic structure is of a heterogeneous nature and the balancing structure has a relatively higher durometer than adjacent forefoot and rearfoot regions.
 13. The sole unit of claim 1 wherein the sole unit comprises a modular assembly of a plurality of layers, one or more layers contributing to the structure of the balancing structure.
 14. The sole unit of claim 1 wherein one layer comprises a core layer with the balancing structure disposed thereon.
 15. The sole unit of claim 14 wherein a second layer comprises a stability layer comprising a cushioning element.
 16. The sole unit of claim 15 wherein the core layer is disposed above the stability layer and the stability layer has a window or frame through which the balancing structure protrudes.
 17. The sole unit of claim 15 wherein the stability layer is disposed below the core layer and an outsole layer is disposed below the stability layer.
 18. The sole unit of claim 1 wherein the sole unit comprises at least one layer serving as a midsole.
 19. The sole unit of claim 18 wherein the midsole layer comprises a resilient material having a lower durometer than the durometer of the balancing structure.
 20. The sole unit of claim 19 wherein the balancing structure is formed on a core layer comprising a resilient material having a relatively higher durometer than the midsole layer. 